An escalator, in which treads are held level, and tracks for going trip and return trip are integrally constructed, is well known. Driving mechanism of such an escalator, however, fundamentally relies on a flexible chain. A disadvantage of the flexible chain resides in difficulty in putting it to practical use. The inventor of present application has already applied for a patent right to the Japanese Patent Office, regarding the invention relating to an endless track conveyor apparatus utilizing a parallel link mechanism with flexible links (the Japanese Patent Application No. HEI 1-230458/1989, which is later published as the Laid-open Japanese Patent Application No. HEI 3-95095/1991). Furthermore, the inventor of this application has applied for a patent right to the Japanese Patent Office, regarding the invention relating to an endless track conveyor apparatus utilizing flexible connecting links and auxiliary guide rails capable of keeping the treads level (the Japanese Patent Application No. HEI 1-241770/1989, which is later published as the Laid-open Japanese Patent Application No. HEI 3-106790/1991). These prior arts basically rely on a method, in which driving power is derived from "pushing" force. In this method, therefore, the connecting links and treads are required to have the rigidity of the connecting links and the treads. However, increasing the rigidity entails a disadvantage such that overall weight of the apparatus increases correspondingly. Furthermore the driving mechanism used in these prior arts employs gears or the like means; therefore, accuracy requirement to be met is too high to put the apparatus to practical use.